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This study investigates the effect of environmental stress cracking (ESC) on the mechanical properties and structural integrity of glass fiber-reinforced polypropylene random copolymer (PP-R) pipes after 3 years of service in a hot water supply system. Despite operating within the manufacturer’s specified parameters, the pipes experienced premature failure. Microscopic analysis of the inner pipe surface revealed longitudinal cracks and characteristic oxidative degradation patterns, identified as typical signs of ESC, likely induced by chlorine used for water disinfection. Tensile tests demonstrated a significant degradation in mechanical performance: the tensile strength of the material decreased by approximately 20% compared to the reference value, and the failure mode was brittle, with no neck formation observed. The elongation at break was 11–14%, making impractical the comparison with the reference value stated as 350% by the manufacturer. It can be assumed that the operational exposure of the PP-R pipes to oxidative agents under stress leads to their embrittlement and premature failure.

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Embrittlement and Tensile Strength Reduction of Polypropylene Pipes Due to Environmental Stress Cracking

  • 会议论文

  • 发表日期：

    2026年

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  • Anna Dontsova,
  • Gleb Averchenko

摘要

This study investigates the effect of environmental stress cracking (ESC) on the mechanical properties and structural integrity of glass fiber-reinforced polypropylene random copolymer (PP-R) pipes after 3 years of service in a hot water supply system. Despite operating within the manufacturer’s specified parameters, the pipes experienced premature failure. Microscopic analysis of the inner pipe surface revealed longitudinal cracks and characteristic oxidative degradation patterns, identified as typical signs of ESC, likely induced by chlorine used for water disinfection. Tensile tests demonstrated a significant degradation in mechanical performance: the tensile strength of the material decreased by approximately 20% compared to the reference value, and the failure mode was brittle, with no neck formation observed. The elongation at break was 11–14%, making impractical the comparison with the reference value stated as 350% by the manufacturer. It can be assumed that the operational exposure of the PP-R pipes to oxidative agents under stress leads to their embrittlement and premature failure.